title: Stable isotopes of nitrate reflect natural attenuation of propellant residues on military training ranges.
abstract: Nitroglycerin (NG) and nitrocellulose (NC) are constituents of double-base propellants used notably for firing antitank ammunitions. Nitroglycerin was detected in soil and water samples from the unsaturated zone (pore water) at an active antitank firing position, where the presence of high nitrate (NO3(-)) concentrations suggests that natural attenuation of NG is occurring. However, concentrations alone cannot assess if NG is the source of NO3(-), nor can they determine which degradation processes are involved. To address this issue, isotopic ratios (δ(15)N, δ(18)O) were measured for NO3(-) produced from NG and NC through various controlled degradation processes and compared with ratios measured in field pore water samples. Results indicate that propellant combustion and degradation mediated by soil organic carbon produced the observed NO3(-) in pore water at this site. Moreover, isotopic results are presented for NO3(-) produced through photolysis of propellant constituents, which could be a dominant process at other sites. The isotopic data presented here constitute novel information regarding a source of NO3(-) that was practically not documented before and a basis to study the contamination by energetic materials in different contexts.
authors.affiliation: Institut National de la Recherche Scientifique, Centre Eau, Terre et Environnement (INRS-ETE), 490 de la Couronne, Quebec City, QC, G1K 9A9, Canada. genevieve.bordeleau@ete.inrs.ca
authors.forename: Geneviève
authors.initials: G
authors.lastname: Bordeleau
authors.forename: Martine M
authors.initials: MM
authors.lastname: Savard
authors.forename: Richard
authors.initials: R
authors.lastname: Martel
authors.forename: Anna
authors.initials: A
authors.lastname: Smirnoff
authors.forename: Guy
authors.initials: G
authors.lastname: Ampleman
authors.forename: Sonia
authors.initials: S
authors.lastname: Thiboutot
mesh_terms: D002851:Chromatography, High Pressure Liquid; D007554:Isotopes / Q000737:chemistry*; D008889:Military Personnel; D009566:Nitrates / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D007554:Isotopes; D009566:Nitrates; D014874:Water Pollutants, Chemical